Converters of the kind initially specified are in particular used in wind turbines which are used not only for generating real power, but which also provide reactive power. To increase network quality, wind turbines are also increasingly being expected by the network operator to provide considerable reactive power on demand. Providing reactive power has become a network service which is a prerequisite in many places for connecting a wind turbine to an energy transmission network and operating it efficiently. It is to be understood that by providing reactive power, normal operation of the wind turbine is preferably not to be affected, and that the wind turbine in particular must furthermore be reliable, in particular gust-resistant.
It is generally possible to provide more reactive power by equipping with larger-sized converters. However, this approach has the disadvantage that it results in exceptionally high costs. Furthermore, it has the disadvantage that, depending on the requirements of the network operator, otherwise identical wind turbines would have to be provided with different converters, thus increasing component complexity. Finally, simply equipping with a larger converter is disadvantageous for retrofitting, as this is exceptionally complex and is in many cases not economically feasible. Therefore, there is a need to refine a converter of the kind initially specified in such a way that it is possible to provide a higher continuous load, in particular for the increased provision of reactive power, despite active components of the converter being unmodified.